Merrill j



- June 7, 1932. A DORCAS 1,862,300

ARC CARBON FOR PRODUCING ULTRA VIOLET LIGHT Filed, Sept. 29, 1927 X FIG.l.

INVENTOR:

ATTORNEYS.

FIG. 4.

10 are.

so Tungsten Aluminum I Patented June 7,1932

PATENT OFFICE,

UNITED sTATEs l HERR1 TLL J. DORCAS, OF CLEVELAND, OHIO, ASSIGNOR TNATIONAL CARBON COM- PANY, INC., A CORPORATION OF NEW YORK J 'ARC CARBONFOR PRODUCING ULTRA-VIOLET LIGHT sirable thatelectrodes used for thispur ose shall emit energy rich in ultra-violet. It is well known thatthe use of various single metals in a carbon electrode will modify thespectral characteristicsof rays emitted by an These various metals havecertain radiation curves due to the fact that they emit radiations ofcertain wave lengths with greater intensities than those of other wavelengths. By combining various metals in a carbon it is possible toobtain a smooth spectral energy distribution curve and at the same timesecure a greater amount of energy near and in the ultra violetradiation. Metals which are useful for securing this desired radiationare cobalt, tungsten, copper,

aluminum, ironand nickel, either as metal or in their compounds. Thesemetals, when employed in the core give prominent bands A as set forthin'the following table, 25

Wave length oii prominent bands 2300-2500 AU 34003600 AU 2600-2650 AU v3400-3500 AU 29003200 AU 2200-2300 AU A 2500-2700 AU 229042300 AU I2900-3100 AU 3400-3000 AU Element in carbon core Cobalt Copper IronNickel Application filed September 29, 1927. Serial N'o.v 222,854.

Thus by the use of properly selected metals in the core the character ofthe radiation may be varied within wide limits.

In the accompanying drawing I show spec tral energy distribution curyesof electrodes containing various metals, the total percent age of metalbeing substantially the same in each case.

In the drawing, Figure 1 represents the curveof an electrode containingiron;

Figure 2 represents the curve of an electrode containing aluminum;

Figure 3 represents the curve of an electrode containing nickel; and

Figure 4; represents the curve of an electrode containing iron, nickeland aluminum. In these figures the line X-X represents the boundarybetween ultra-violet and .visible light. I

From an examination of these curves it will be apparent that acombination of the three metals will give a greater amount ofultraviolet radiation than will a corresponding amount of any singlemetal. It will also be observed that the radiation is more evenlydistributed over the entire ultra-violet spectrum in the case wheremixtures of the metals are used, than in the'case where a single metalis use While I may use a solid carbon with the metal distributed evenlythroughout, I prefer to use a cored carbon containing the metal mixedwith the core. While various amounts of metal may be-used in the core Ihave found it desirable to limit the amount of metal to 50% of the coremix or from 5 to 10% of the 1 total carbon. In preparing electrodes ofthis type a shell is formed by extruding a mixture of carbon and,binder, forming a hollow tube. This shell is baked at a temperature ofabout 1400 C. A core mix consisting of carbon, a binder and up to 50% ofmetal is prepared and forced into the shells after they have been cut toapproximately the length desired. The electrodes are then heated toharden the core, the tem erature re uired de ending upon the type binderemp oyed.

vhile I may use various compositions for the core mix the following isgiven as typical.

Parts by weight Iron J 23.4

Nickel I 19.5

Aluminum 4.5

. Carbon flour 42.6

Potassium silicate 10 In this case the metals are in substantially equalproportions by Volume.

While I have found it desirable to employ substantially equalproportions by volume of the metals added to the core, I do not wish tolimit myself in this respect as various proportions may be used,however, in any case at least two metals would'be present to at least 1%of the core mix.

I claim:

1. A batch for forming cores for electrodes consisting of ironsubstantially 23 parts by weight, nickel substantially parts by weight,aluminum substantially 4 parts by weight, carbon flour substantially 43parts by, weight, and potassium silicate 10 parts by weight. w v

2. 'An elect-rode for are lamps comprising a. a relatively hardcarbonaceous shell and at relatively soft core, said core containingcarbon, a binder and substantially 20 parts of nickel, 23 parts of ironand 4 parts of aluminum byweight.

,3. An electrode for are lamps comprising a relatively hard carbonaceousshell and a relatively soft core, said core consisting of iron,aluminum, nickel, carbon, and a binder, the combined weight of thethreemetals being substantially of the entire core.

4. An electrode for are lamps comprising at least 90% of carbon andbinder, with the balance nickel, aluminum, and iron, each oi said metalsbemg present in an amount of at least 1%." i y In testimony whereof, Iaifix my signature. 1 LIERRILL J. DORCAS.

